Commutation of multiplex armature windings



Nov. 17, 1931. I J HULL 1,832,703

COMMUTATION 0F MULTIPLEX ARMATURE WINDINGS Filed Jan. 17, 1930 Inventor:

John I. Hull by MM His Attornes.

Patented Nov. 17, 1931 warren STATES PATENTO E JOHN I. HULL, or SCEZENECTADY, NEW YORK; Assronon'ro GENERAL ELECTRIC com- PANY, A CORPORATION or NEW YORK COMMUTATIOlN' or MULTIPL ARMATUREI WINQI'NGS Application filed January 17, 1930. Serial No. 421,537.

My invention relates to dynamo electric machines having commutated windings and the principal object of my invention is to improve the commutation of such machines.

In dynamo electric machines having commutated windings it frequently becomes desirable to improve commutationby having a lower value of induced voltage between adjacent commutator segmentstlian thatcor responding to one turn ""surrounding the entire working flux of the machine. Withthe commonly usedplain multiple windings this is not possible 'xce'pt by the use of fractional pitch windings? Where low iractional pitch 16 windings areus ed there are attenda 'eyils such as reatly incre'ased c c'ippi'liflos s'csf d a relatively increased im. ortance' of harm volta ges compa'red to t f i ii idamental 1t:- ages and these disadvantages strongly c 11in,- 20 teract any gainstocOnimutatiOn that-might result from the use It therefore became desirable to jiiseifall e ly ful p t h r nd em' i et thes time have a loyver valuej of i" du c 'ediy' ltage between adjacent comment, 1' v lt than that corresponding to .oneltt-qrl li irou nding the Working flux" of the riiacliinej 'llhis desir-able, object is obtained by meanst knov nto those l z i1led., the ,asfsh fiii forexamplein U nited States .I -ettc rsl rit 3 2 .45; Deho ssi d.t wh w fi of this inuentionlfl Figlf'l of the above mentioned patent-dis closes an ordif'nary full pitch" orflnzirlyfull pitch multiple iyzfinding iuJYhiChtheendS of each coil are connected to: alternate commu tator' segments with the so -,callecl ..equip0ten: tial leadsconnecting the intervening commutator segment to the middle point ofithe coil at the end of thearmature opposite the commutator. Fig.2)? the abovementionedpat out is similar to Fig. 1 eXceptthat a njaddi? tional windingis connected to thein'ter ven iug: commutator segmentsand the-two windinns are of unequal pitches and henceFig. 2 d sclosesa duplex winding with equipo teutial leads. It is evident that in Figs. 1 and the induced voltage between adjacent com- :imtator sesnnents will be one-half of the voltage induced in a coil and in addition there will be a uniform voltage gradient between adj'acent commutator segments although this may be accompanied by a slight flow of equalizing current in the equipotential leads. It is evident that the" induced voltage between adjacent commutator segments is reduced for a givens'i'zeof machine or conversely'the size of machine" may beincreased'for a 'given induced voltage between adjacent commutator segments. f '-'It"'i's we'll knowngto thoseskilled in t-he art; that the resulting advantages will be either-improved commutation *for; a givenfsi ze oi {machine or an increased size of--'- machine for ai gii'ren "degree "off c'ommut'a new both *a'dyanta'ges in? part'may -Iie ha'dg It will beievident that altliou'glftlre commutation-has" begga -greedy ha iroved'ltherefi may' b e' certain liiQllht df sparking :because there; still remain induced voltages between adjacent commutator sag thecoilsshortcircuited by thebriislie's'du to the "co mutation process; 5 itselfi It i'folloi vs that additibna'hmea'n's'fliiustlie eifipfloyedfii at is deslred'ito reduce these iiidu'ced wing-e and-'thereb'y furthe proi ethe c'ommutaj i following discussioii l 15 6- to obt'ainf snarklesscommutation in a"di rect current" and' -in a siri'glegplfa s e alternating current machine (morecorr'ectly callcdtyvophasefthe current in the coi'l'short' qrcu ted by the bru'sh must'reverse tha'tis change 180 jelectrical degrees as' it passes under the brush whereas i na t2 phas ef alternating cur.- rentmachine more correctly called lgphase) the current must changQO :electrical de'grees and in a' 3 -ph ase alternating current machine the current" must change 120 electrical deing magnetic flux induces a counter-electroinotive fOIQQ i pthecqil thgtgppg fl 5 r nt reversed therein. Thd fl g a nas ings to improve commutation. My invention will be bestunderstood from the following description when considered in connection with the accompanying dran'in s while greatly decreased by the damping z c tign qf l:ig. l represents :1 preferred embodiment the remaindei of the armature windings is now evident thagsinee the coil is g p of 'another currenfpat'hoftli against. its self-induced,- counter-electromd tive-ioroewr as ;is -,usua1-im=suchleases the current formsmn :alcover theiniica (insulin tion between! the commutatonzegmentsmd reaches the. brush :without: passingjethrough =--;:vw-: fr-r-ugfi-zz 41-1-01 i-ui q-zf 'i' i It is desirable toolgtaimspfllddsscoinmutm tien-and; hence:nearlymlhdynmndeleotnimmm chines -haying- -stationfamy ibt'lishes'such-asdir rect current and nonabmshshiztfiihg alternating; cunent commutator employdnterpole mtindingszmhose function it i duceg-s'ql agg hshontdimuited eo wh eh' mntemelecm :metwe-iemmwdeavei mislight stirexwe fil -g9 il tq qs's fit the curmnt neihere fliitqsmndmtrtheo fbi evflmt ll i .ngi 1. mmi qgmmt.em.piair-interp w d e sfi fiaep ewe mmuwtimmflhe speed of; the lprush-. s1 1i fti1 1,;, -,alternating-v dun e com eme rz eew 'can b m ly varied b h fi i gsi slb tuebesend it. .4;hereore? e s; d s re l ete empleymthenzmeanstw zt tsim xweiit .cqmmfifihneni-thm l de h h le fi h e eir fimntemM ims means heve been, proposed. anti HS QWO prove its .com ;nut2g1 ipn,; exemples i 015', such b gseerie -ie r es smn sz e ween the cimin'iutatoisegments to function as;dis,- u ?x s et e s ensluem al-imind nga to s t e it ndi du qh eihaembe r ex. b lh s? sisimile; fi wlsr-e gen i ete he constructiou ofithe inc penso Mp i exzwi ei r-ts-re e i 1 vith 'equipote itia l ,comgections to improve sem iu n ie s-i l h e d sc y 'edt b tn rhe such? \yIindi 11 s, are: used, :I cam, mtg hgq them and t fi fi mfii =ill n l-me s: that i 9i lfl 1 sdditiqnel r9 n on t n es 2 w d e t e ov beginemal mflisfha 'ingt e'e se ci s surro'unding' indiyiduql teeth-5n; such a. man; net as to 'greatly .impro'e connnutation It will. be evident that mjim ention vzilhequa ly apply to any dynamo electricmacl ineghevjing 1i eommutated winding, butit-s. greatest use willprobably be the alternating cur rent brush shifting commutztto niotoi; since these m w ei 'iefi i ele nd; w m dle;

erms A winding the current from.thisgthegpath ggnfglqpgfl reach the brush either through the coil m'g'thethe features of my invention which are beheved-to novel and pate ntahle are pointed outfin .the'iarmsappended hereto.

of my invention appliedto a duplex wind- .p'resents a prcferred' eonof-fharmaturc core. and spider fgr- .cei'yyiug theequipotentia1 leads.

efc il'iiigf Fig. '1. 10 i'c njeszcutfi 1!. (la-- section of;thug-(muuutntor. com -isgnieiits IL 12,13, 14. 15 and H; which ame-sepalzateil by suitabZe-insulatin inat'erlai ,amd 1J represents-nag bruslptestis] onthe ,segmmltsrl2 and 13, but it to be-undexstcod thatgthe, machinecmpioyingihis ivinding willhgve at leastgtwo brushes spa-(19d at 0; p;n ,si-te.'e polarity points? on. the commutator. Egg the spec? .;-1ubodiment.ot the invention z' w-Fe eliigeh-e e dur hzs u n lid seeeh e. bi-ids ne oa mwe v.= 1in ewiitetem m etsfi mingenom M c? eememt ee i ..-i .o-.s snslei sd-s.e t p s 9f th newts-Renews -nelipl ry we e? b5; lfi n d The sectionlShesthe eeng zesaleh -21 e d? 7 5 9E lwafin,pes n r-ale e end 5 11, eeqgsemse b zweee; h w-' fit u e$ nh .mie it es i at bfi de e '11.: pitches :u-e shown,

t i connect t igsswzos 36"atthe winding ends oppositetlie commuztator, One ot- :the :armaturecoreitee'th is represented by 58 and- @T represents the magnetic flux in this tootlv and for illustration the direction of'this magnetic flux is-showu by the arrow 59. 1 Inspection of- Fig.1 1 -Will show that. the coils ofboth windingshave-thesame winding pitch and that each core slot contains corresponding slot conductors from one coillof each winding; as for example ,-the slot--21 contains the corresponding 1 slot conductors 43-and49 of coils 33 and ,34and the slot 29 contains the other. corresponding slot conductors 44 and of the ccils 33 and. 34. The ends of the coils 32, 34 and-36 are connected to the alternate segmentsll; 13 and 15 and the. equipotential leads 5ft a1 1d: 57 connect the middle points oi, these coils-to the intervening segments. 1 2};- l4 and .16, and he tel age etenadia e 0mnm m' segments will correspond 1 to f the voltage [inducedin one-halfof-a goil.;;-;-'I he;= e i ids of the e sfi i- 5 4.3 et ia se cen eetedit th n srreninase ee a12 1 4a dl iit iiscan; necting equal potential points in tl ye1 two w ndin s.and;ins rin iaeunifeim '0 a dient et-r en adies n mnuita o a a alth h it ism shtbs. ee mpeme iti s i h iflera f eni'el iii ae tr iitrimt e eq re iifiie i ad ew ieadhlu ill ebri sh h meseemtate scs: fi ffi 1 i m meti m i in t i s .I. i v.1 hlch consists of s,

- Bill a he indepe dsntwindinssr eth i g te Q: t y H h r. ina eacharmatiire c. e

the

mections 47 and 46, slot conductor 44, end connection 45, equipotential lead 56, end conuection=53, slot conductor 49 and end connections 54 and 39, thus completing the circuit to the starting-point. The direction of current flowin this secondary path at any instant may be illustrated for example by the arrows shown on its "arious portions. It is evident that the primary circuit is completed through the; segments 12 and 13 and the brush 17 whereas the secondary circuit is always closed .without'the aid of commutator. segments or brushes. It can be. seen that the primary circuit forms a part of the secondary circuit so there really exists an auto-transformer in which the slot conductor 38 acts as the primary, the tooth 58 acts as the magnetic core and theslot conductors 38 and 44 act as the secondary since they are on opposite sides of the tooth 58 and the current flowinthem is in opposite directions and hence they are inductivelyrelated to thetooth 58. The remainder- 0f the secondary circuit is nearly non-inductive because theconductors 43 and 49arejin the same slot and the current flow through them andin the remaining adjacent confl uctors is in opposite directions.

-{lhebenefits to commutationresulting, from these, secondary paths may betdescribed as follows ,It-is wellknown to those skilled in the art; that the; primaryof a transformer drayvsacurrentfrom its sou 1'ce of supply to set up the m agnetizingfiuxof thetransfgrmenand When the secondary circuit of the transformer .is: closed the current-flow in the secondary- .tend s to demagnetizethe transformer and ,the primary mustrdrawan in creased current tomaintain' the magnetizing flil -ii ui sy de h t t ur nt reversal in;the;,described primary circuit of the armature winding tends to set up a magnetic flux in the, tooth, 58,;thus inducingea voltage and resulting current:flowv in, the, described sec,-. Wid st c i i f 9f th -h mste W n jygh ich in turn tends to neutralize the flux set pp; the primary current-.1 Thet prirnary current is limited bythe value ofthe current i.n:one.of the armature paths and therefore primary current cannot automatically increascto. maintain this magnetic flux. The result is that only a small value ot' mae netic flux, is :sethup in the tooth 58- by the primary current, thus gzreatly reducing the induced grount erfele-ctromotive force :in the primary an di qreatlyfi -improvingi commutation. Similar, actionrtakes placerat every hrusl'i on: the commutator flrqiardlessj of which two accntf commutator segments the brush restsou asthecommiitator rotates. It is evident however that the slot conductorscarry the induced current in addition to theload current and the equipotential leads carrjrthe induced current in addition to the possible equalizingcurrent. Examination of Fig. of United States Patent- 1','Z39,415 wil]1lshol=w that fhe effect-of current carrying: coils-l; surroimding-neach tooth can not be obtained-sincesuchxcoils would contain two conductors cairryingcuitrents in'oppostediiectionsg on each side of the tooth .u'hich causes their induced voltages to oppose and balance teach-other and thus no locally induced currentsscan: flow in suchcoilswi. -'3 f' Figg'i of my invention represents a pre- 'ferrd construction of the armature coreand spider for carrying the equipoteiitial lead-s. In Fig- 2 similar -reference-=- characteis to those used in Fig.1 represent oneicoil and one equi iotential lead connected tothe co nmutator. "-Itis preferablelto place-the.et1ui'- potential leadsin openings ot'the spider 60 but if 'desired'the'y may' be' carri ed in any suitable mannerwell' knoivn to those skilled in t heg rt l f zIt 'w ill"-' be' readily *appreci ated by' those skilled in the art thet my invemjdnwilinot only improve commutation in the above described mannepbut iti w ill alsbfihaire hstrong tendency to suppress the 'objectitinab le'high frequency ha monicwhleages dueto thepassage of the rotor fteetl flpa st the ist'atojr' slots, phflS6- jbl ts' of; winclings; pifich eflectsg etc. This will tend to'redtice the' core losses which togetherwith the eeddetlidh imlo'ssesec the bm'sh's flu to thei'pfttctii'calf eliifiiiiatioriof sparking will greatIyfofi-sefll' oi ma even more than beset? theqbsses esuseli by the injdfiqea current fiew's v the lhea ishower cuite'd 'pathseurrmmthjn 'etcu teothifl it "{Th tendencyto spitrkf itflili hrushe will increase whef wu mew- 1 rahs ahb e' syn gsrmiism witm h'i imverm ssmeeajaargr vai'ueof benefit as d et fveis'edin thqcoil lf hstv tsted myflinve'n tion by sp -r ing it tof biiusn'gshini'n'g arise Dating buried? c'bhnii utathi' motors Wi fliQht int'rpale-wj din' s'a'ridthcoirfifliit tidrcwis highly! sari moth eves With f-"opefatfoii above eyschranisiwne hfghil Q'vrload's, whereas my difsdtifbtd' commutation res nsist ng" same s wicu s'imilai operation and meg use of t I oidinali'yjbel ii 3-; i lt i's evi'dent'tliah 7 to"ilnjirotelcommutiit oniiiiltliotgli clii iie 'has; internals windings foiitliis pur 656; hate momma ifi.in'i eiition 1 in connection' ivith e'jdt'ipl windingiziii an ged so 'th'afl'e'zich local sho" i'r ciiited'fptth isin duc'tively' related 'to' one toothj hut it will 'be obvious to those slgill edf 'in ii'r tf th at my inv'en tiou wilr eqqanyj'sp'piy toiany multiplex winding! arrztiig ed so that each local short-circuited 'p'ath is"inductivel'y related to one or more than one toothl Accordingly I wish it understood that myinvention is not to be limited to the exact'means' shown and that such-other modifications as all within the true spirit'and scope of my in- Vention are intended to'be included within the scope of the appended claims.

-What I claim as new and desire'to secure by Letters Patent of the United States,'is: v 1. An armature for a dynamo electric machine comprising a magnetic core having a plurality of slots, a windingconsisting of coils assembled in said slots, another winding consisting of coils assembled in said slots with the same winding pitch as the coils of the first mentioned winding, each of said coils containing at least two slot conductors, said coils being so arranged on said core that each slot contains the corresponding slot conductors of at least-'onc'coil from each Winding 'a commutator consisting of spaced segmcntswith every other segment connected to the coil ends of the first meutioncd'winding and the intervening segments connectethto the coil ends of the secondmentioned winding and connecting means between the'said intervening segments 'and the approximate center's ofthe c ils of the first mentioned winding." 21 An armature for. a dynamo electric'miichine comp'iis n'g 'a magnetic core havin a plurality of slots} a plu'ralit yoflfap Wind} igigs consis'tingi'of' coiljs'j assembled-iii said 'srots' with the seinewinding"nitbhiiliiii s'a'i d"-qdi1scontaining at least 'tivo "islotc'ohdutofsl suid'coils'lieiiig sd airaiig ed onsaid core that 1 each slot contains the co'ri'es iond slot-"conductors of at least one eacliof "windingjgl' a "commutator coii Sistin f s'fiacedf 'scgmentsgii ith the oriee i t" i e tb w en e xnme i slot pnn "meme;" 9 Fin te-beseee sI non e e 'imeemem s-epiiro'xim'ately equi'potential n "of t "said I a w t d' n s. .v e r 3.1ArrarmatIuJre foi' 'd'iui mo comprising a 1 ofiudepend iit of iii f Sl t iiiitt I esporiding slot con; dlictors fi'om zit least one coil offeacli'win'cl iiig, a commutator consisting o fl sne ed segriients, means tor connectii "the c s' iond} ins: sloflconiductors lying i I oni nortslot-s to ed agent commutator scgm'e ts i n the :order in" ivhich saidfslots are It; v coregaud means for indi 'i uf y connecting s s al erna e ev-m tate sme l t api roxi matecenterof tha "coil Whose ends are connected to commut or se'sime nts locat; ed jon both sides of the rt iiectivealternate commutator segment.

4 An armature for a dynamo elet .ric machine comorisine; a maouetic core having a; plurality of slot-eta ,olur of iiide ncndent lap windingsconsisting'ofcoils having was. hiking the i around said the same winding pitch assembled in said slots, each of said coils containing at least two slot conductors, said coils being so arranged on said core that each slot contains the corresponding slot conductors of at least one coil from each of said windings, a commutator consisting of spaced segments, means for connecting the corresponding slot conductors lying in a common slot to adjacent commutator segments in the order in which said slots are located around said core, brushes bearing on said commutator, each brush having a width capable of brid 'ng only two adjacent commutator segments uring operation of said dynamo electric machine, and connecting means between approximately equi-potential points of said windings.

5. An armature for a dynamo electric machine comprising a magnetic core having a.

plurality of slots, a lap winding consistlng of a plurality of coils, a second lap winding consisting of a plurality of coils having the same winding pitch as the coils of the first mentioned winding, said coils being so arranged on said core that each pair of slots separated by a distance equal to the winding pitch of said coils contains one coil from each of said windings, a commutator consisting of spaced segmentsmeans for, connecting the ends of the coils of the" first mentioned winding to alternate commutator segments in the order in which said coils of the first mentioned winding are located around said core, means for connecting the ends-of the coils of the second mentioned winding to the intermediate commutator segments in the order in which said coils of the second mentioned winding are located around said core, means for individually connectingeach intermediate commutator segment to the approximate center of that coil whose ends are connected to the segments adjacent to the respective intermediate segment, and brushes bearing on said commutator, each brush having a width capable of bridging only two commutator segments during operation of said dynamo electric machine.

In witness whereof, I have hereunto set my i hand this 16th day of January, 1930.

JOHN I. HULL. 

